نشكر إدارة معهد ماساتشوستس للتكنولوجيا الكيمياء واللجنة المفاهيم معهد ماساتشوستس للتكنولوجيا لنكولن مختبرات متقدمة لدعم هذا العمل.

<ol>
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والكتاب ليس لديهم ما يكشف.

والميزة الرئيسية لحزب البعث العربي الاشتراكي التوليف فرشاة الأول هو قدرة فريدة على تجميع بسرعة النانو من حجم متنوعة وتكوين بالتوازي دون الحاجة إلى المعدات المتخصصة. في هذه الدراسة، ونحن لشرح طريقة الفرشاة الأولى الاصطناعية باستخدام في norbornene بين functionalized PEG macromonomer <st...

وقد درس على نطاق واسع النانوية البوليمرية للاستخدام إمكاناتهم كما منصات لتسليم المخدرات، الحفز المعتمدة، التصوير البيولوجية، والتجمع الذاتي 1-3. تتطلب التطبيقات الحديثة التي التوليفات جسيمات متناهية الصغر تكون سطحية، واستنساخه، ومتوافقة مع وظائف الكيميائية، وقابلة للتنويع 4،5. عصابة فتح الابدال والاحلال البلمرة (مرح) الأوليفينات توترت هي منهجية قوية لتجميع النانو البوليمرية وظيفية مع أحجام للرقابة والتوزيع الشامل الضيقة 1،6-8. على سبيل المثال، بين functionalized في norbornene-بولي (جلايكول الإثيلين) (PEG) macromonomers (MMS) يمكن بلمرة بكفاءة عن طريق مرح لتوليد البوليمرات للذوبان في الماء زجاجة فرشاة. باستخدام هذا النهج، النانو التي تحمل جزيئات متعددة نشره المخدرات، fluorophores، وكلاء تدور على النقيض يمكن أن يكون مستعدا بسرعة وبالتوازي 6 و 9 و 10. ROMP كما تم استخدامها لتخليق &quot;تسليح والعشرين&quot; من البوليمرات نجوم. في طريقة الذراع الأولى، يتم crosslinked بوليمرات خطية مع crosslinker متعددة الوظائف لإعطاء النانو كروية مع الأسلحة البوليمرية. ذكرت شروك وزملاء العمل أول التوليف مرح الذراع الأول من البوليمرات نجمة عبر يشابك من في norbornene، dicarbomethoxynorbornadiene، وtrimethylsilyl المحمية dicarboxynorbornene البوليمرات الخطية مع crosslinker في norbornene bifunctional 11، 12 Buchmeiser مددت هذه المنهجية لتخليق المواد مع مجموعة من التطبيقات التي تشمل الحفز المعتمدة، الأنسجة والهندسة، واللوني 13-17. جعلت أوتاني وزملاء العمل النانوية نجمة البوليمر مع الأسطح وظيفية عبر &quot;في الخارج&quot; استراتيجية البلمرة ذات الصلة 18، 19. تنطوي معظم polymerizations الذراع أول تفاعل معقد من مونومر، البوليمر، ونجم اقتران ردود الفعل. اله عائدات الأخير عبر آلية خطوة النمو الذي يؤدي عادة إلى الوزن الجزيئي واسعة (MW) التوزيعات. للتغلب على هذا القيد في نقل ذرة تفاعلات البلمرة الراديكالية الذراع الأولى ذات الصلة، يقوم Matyjaszewski وزملاء العمل الذراع الأولى يشابك من الرسائل المتعددة الوسائط البوليمرية مسبقة التشكيل لتوفير البوليمرات نجوم مع توزيعات ميغاواط ضيقة جدا 20. في هذه الحالة، فإن الجزء الأكبر الفراغية من رسائل الوسائط المتعددة، ونسبة زيادة الأسلحة نجمة لاستهلال الإجراءات المواقع، تحول دون عمليات نجمة + نجمة اقتران تسيطر على نحو رديء، وأدت إلى لقمة العيش، وآلية النمو السلسلة. عندما حاولنا نفس الاستراتيجية في سياق مرح مع منتهية في norbornene PEG-MM وcrosslinker مكرر في norbornene، تم الحصول على البوليمرات نجوم مع واسعة جدا، وتوزيعات ميجاوات متعدد الوسائط. اقترح هذه النتيجة أنه في هذا النظام MM وحده لم يكن ضخمة بما فيه الكفاية لمنع نجمة + نجمة اقتران. لزيادة الجزء الأكبر الفراغية من الأسلحة نجوم، ويحتمل أن تحد من هذا uncontrolled اقتران، حاولنا تتبلمر أولا MM لتشكيل البوليمرات زجاجة فرشاة في غياب crosslinker ثم قم بإضافة crosslinker. كنا سعداء للعثور على أنه في ظل ظروف معينة، وفرت هذه &quot;الفرشاة والعشرين&quot; أسلوب الوصول مباشرة إلى &quot;البوليمرات نجمة فرشاة الذراع&quot; (BASPs) مع توزيعات ميغاواط الضيقة والانضباطي الأساسية وظائف الهالة. نحن ذكرت مؤخرا تركيب مرح فرشاة الأول من BASPs PEG باستخدام جرابز 3 الجيل الثالث المحفز A (الشكل 1) 21. في هذا العمل، والتعرض للPEG-MM B إلى A حافزا لدت macroinitiator فرشاة المعيشة مع تعريف طول العمود الفقري (B1، الشكل 1). نقل مأخوذة من B 1 إلى قارورة التي تحتوي على كميات مختلفة من crosslinker C بادر حزب البعث العربي الاشتراكيتشكيل. ميغاواط، وعلى هذا فإن الحجم، من BASPs زيادة هندسيا مع كمية من C المضافة. قدمنا ​​فرضية الآلية لهذه العملية نمو هندسية وأثبتت أن ظيفية، nitroxide والأساسية BASPs المسمى الاكليل يمكن إعداد بسهولة دون الحاجة للآخر البلمرة-الخطوات تعديل أو إضافات مونومر متسلسلة. ومع ذلك، في كل من الأمثلة المبلغ عنها، كنا تشعر بالقلق إزاء حافزا التعطيل، ونحن نفذت جميع التفاعلات تحت N 2 الجو داخل صندوق قفازات. منذ التقرير الأولي لدينا، فقد وجدنا أن الأسلوب فرشاة الأول هو فعالة جدا لتشكيل BASPs من مجموعة واسعة من الرسائل المتعددة الوسائط منتهية في norbornene وcrosslinkers الوظيفية. اكتشفنا أيضا أن الأسلوب لا يمكن أن يؤديها على الفوق مع عدم وجود احتياطات خاصة لإزالة الهواء أو الرطوبة. هنا، سيتم SY سلسلة من ثلاثة BASPs من اختلاف ميجاواتnthesized من خلال طريقة فرشاة الأولى في ظل الظروف المحيطة. باختصار، سوف يتعرض 10 في حكمه من B إلى 1.0 في حكمه من حافز A (الشكل 1A) لمدة 15 دقيقة لتسفر عن BI بمتوسط ​​درجة البلمرة (DP) 10. وسيتم نقل ثلاثة aliquots من هذه الدفعة من BI إلى قارورة منفصلة التي تحتوي على 10، 15، و 20 في حكمه (N، الشكل 1B) من C. بعد 4 ساعات، وسوف تطفئ polymerizations عبر إضافة إيثيل الأثير الفينيل. سيتم تميزت ميجاوات نجمة البوليمر والتوزيعات ميغاواط باستخدام أداة هلام تخلل اللوني مجهزة للكشف عن تشتت ضوء الليزر متعددة زاوية (GPC-مولات).

<table border="0" cellpadding="0" cellspacing="0" width="592">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="42">
			<td height="84" rowspan="2" style="height:84px;width:216px;">Grubbs Second Generation Catalyst</td>
			<td rowspan="2" style="width:91px;">Materia (or Sigma Aldrich)</td>
			<td rowspan="2" style="width:119px;">C848 (Sigma Aldrich: 569747)</td>
			<td style="width:167px;">
			Used as purchased from manufacturer. 
 *Provided as a generous gift.
			</td>
		</tr>
		<tr height="42">
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Pyridine</td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">270970</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">O-(2-aminoethyl)polyethylene glycol 3000</td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">07969</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">PEG-MM</td>
			<td style="width:91px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td style="width:167px;">Synthesized following reported procedures (Ref. 21, protocol 1)</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">norbornene-N-hydroxysuccinimidyl (NHS) ester</td>
			<td style="width:91px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td style="width:167px;">Synthesized following reported procedures (Ref. 21)</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Bis-norb-NBOC Crosslinker</td>
			<td style="width:91px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td style="width:167px;">Synthesized following reported procedures (Ref. 21)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Pentane</td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">158941</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Tetrahydrofuran (HPLC grade)</td>
			<td style="width:91px;">Sigma Aldrich </td>
			<td style="width:119px;">34865</td>
			<td style="width:167px;">Dried and purified over a solvent purification columns </td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dichloromethane</td>
			<td style="width:91px;">VWR </td>
			<td>BDH1113-4LG</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Acetonitrile (HPLC grade)</td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">34998</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Acetic Acid </td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">A6283</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sodium sulfate </td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td>239313</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Diethyl ether</td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">673811</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dimethylformamide (HPLC grade) </td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">270547</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Lithium Bromide</td>
			<td style="width:91px;">Sigma Aldrich</td>
			<td style="width:119px;">213225</td>
			<td style="width:167px;">Used as purchased from manufacturer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">MillQ Biocel A10</td>
			<td style="width:91px;">Millipore</td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Beckmann Coulter HPLC (127p solvent module, 166p detector)</td>
			<td style="width:91px;">Beckmann Coulter</td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Zorbax 300SB-C18 PrepHT reverse phase column </td>
			<td style="width:91px;">Agilent</td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">1260 Infinity Liquid Chromatography </td>
			<td style="width:91px;">Agilent</td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">GPC KD-806M column</td>
			<td style="width:91px;">Shodex</td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Dawn Heleos II Light Scatterer</td>
			<td style="width:91px;">Wyatt</td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Optilab T-rEX Refractive Index Detector</td>
			<td style="width:91px;">Wyatt</td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glass Scintillation Vials - 40 ml</td>
			<td style="width:91px;">Chemglass</td>
			<td>CG-4909-05</td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glass Scintillation Vials - 4 ml </td>
			<td style="width:91px;">Chemglass</td>
			<td style="width:119px;">CG-4904-06</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Glass Scintillation Vials (PTFE-lined cap) - 2 ml </td>
			<td style="width:91px;">Agilent</td>
			<td>5183-4518</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Stir-bars</td>
			<td style="width:91px;">VWR</td>
			<td style="width:119px;">5894x</td>
			<td style="width:167px;">various sizes </td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">13 mm 0.45 &#181;m Nylon Syringe filter</td>
			<td style="width:91px;">PerkinElmer</td>
			<td>02542903</td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">13 mm 0.45 &#181;m polytetrafluoroethylene syringe filter</td>
			<td style="width:91px;">PerkinElmer</td>
			<td>02542909</td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1 ml disposable syringes </td>
			<td style="width:91px;">VWR</td>
			<td style="width:119px;">53548-001</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Swing bucket centrifuge or similar</td>
			<td style="width:91px;"> </td>
			<td style="width:119px;"> </td>
			<td style="width:167px;">Should be able to reach approximately 4,000 rpm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Round bottom flask</td>
			<td style="width:91px;"> </td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fritted glass filter assembly </td>
			<td style="width:91px;"> </td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Rotary Evaporator </td>
			<td style="width:91px;"> </td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Balance </td>
			<td style="width:91px;"> </td>
			<td style="width:119px;"> </td>
			<td style="width:167px;"> </td>
		</tr>
	</tbody>
</table>

particles without a box: brush-first synthesis of photodegradable peg star polymers under ambient conditions

سوف أساليب مريحة ل، والتوليف المتوازي السريع للالنانوية بين functionalized بتنوع تمكين اكتشاف تركيبات رواية لتسليم المخدرات، والتصوير البيولوجية، والحفز المعتمدة. في هذا التقرير، علينا أن نظهر التوليف المتوازي للفرشاة الذراع نجمة البوليمر (حزب البعث العربي الاشتراكي) النانوية من قبل &quot;فرشاة والعشرين&quot; الأسلوب. في هذه الطريقة، يتم بلمرة بولي منتهية في norbornene (جلايكول الإثيلين) (PEG) macromonomer (PEG-MM) أولا عن طريق فتح باب خاتم الابدال والاحلال البلمرة (مرح) لإنشاء macroinitiator فرشاة المعيشة. ويضاف جزء من هذه البادئ محلول المخزون إلى قارورة التي تحتوي على كميات متنوعة من photodegradable مكرر في norbornene crosslinker. التعرض لcrosslinker يبدأ سلسلة من فرشاة تسيطر kinetically + فرشاة وردود الفعل اقتران نجمة نجمة + يمكن أن ينتج في نهاية المطاف BASPs مع النوى تتألف من crosslinker وكورونا تتألف من PEG. حجم حزب البعث العربي الاشتراكي النهائي يعتمد على كمية crosslinker المضافة. نقوم بتنفيذ SYNالأطروحة من ثلاثة BASPs على الفوق مع عدم وجود احتياطات خاصة لإزالة الهواء والرطوبة. وتتميز العينات بواسطة اللوني هلام تخلل (المؤتمر الشعبي العام)، ووافق النتائج بشكل وثيق مع تقريرنا السابق أن تستخدم الخاملة (صندوق قفازات) الظروف. وتناقش الملامح الرئيسية العملية، ومزايا، وعيوب المحتملة للأسلوب الفرشاة الأولى.

ويبين الشكل 2 GPC يتتبع لمجموعة متنوعة من BASPs أعدت من B1، B2، B3 و. في جميع الحالات، توضح البيانات أن زيادة مكافئات من crosslinker (N) يؤدي إلى زيادة في حجم حزب البعث العربي الاشتراكي. كما لوحظ في تقريرنا السابق، و 10 من حكمه crosslinker ليست كافية لتحقيق BASPs م?...

Watch this Scientific Journal Video about Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions at JoVE.com

Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions

يتم توليفها بولي (جلايكول الإثيلين) (PEG) البوليمرات نجمة فرشاة الذراع (BASPs) مع توزيعات الشامل الضيقة وأحجام نانوية الانضباطي في حلقة عبر فتح الابدال والاحلال البلمرة (مرح) من macromonomer PEG-في norbornene تليها نقل أجزاء من المعيشة نتيجة البادئ فرشاة لقارورة تحتوي على كميات متنوعة من جامدة، وصور شطورة مكرر في norbornene crosslinker.

الجسيمات دون مربع: التجميعي فرشاة والعشرين من Photodegradable PEG البوليمرات ستار في ظل الظروف المحيطة

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug ...

particles-without-box-brush-first-synthesis-photodegradable-peg-star

Research

JoVE Journal

Chemistry

39.6K Views.  Massachusetts Institute of Technology.  يتم توليفها بولي (جلايكول الإثيلين) (PEG) البوليمرات نجمة فرشاة الذراع (BASPs) مع توزيعات الشامل الضيقة وأحجام نانوية الانضباطي في حلقة عبر فتح الابدال والاحلال البلمرة (مرح) من macromonomer PEG-في norbornene تليها نقل أجزاء من المعيشة نتيجة البادئ فرشاة لق?...

Video: Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

طريقة بسيطة لحجم تجميع الشواهد من الكتل بلازميدة قليلة القسيمات مستقرة من جزيئات الذهب في ظل الظروف المحيطة

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

Visualization of Ambient Mass Spectrometry with the Use of Schlieren Photography

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass spectrometer, it is necessary to characterize and understand the physical principles of the source. Most commercial ambient ionization sources utilize jets of nitrogen, helium, or atmospheric air to facilitate the ionization of the analyte. As a consequence, schlieren photography can be used to visualize the gas streams by exploiting the differences in refractive index between the streams and ambient air for visualization in real time. The basic setup requires a camera, mirror, flashlight, and razor blade. When properly configured, a real time image of the source is observed by watching its reflection. This allows for insight into the mechanism of action in the source, and pathways to its optimization can be elucidated. Light is shed on an otherwise invisible situation.

This paper presents a protocol for the visualization of gaseous streams of an ambient ionization source using schlieren photography and mass spectrometry.

تصور المحيطة الطيف الكتلي مع استخدام انعراجي التصوير الفوتوغرافي

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass ...

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

A protocol for the synthesis and characterization of diffusive motion of cyclic polymers at the single molecule level is presented.

توليف دوري البوليمرات وتوصيف تلك الحركة ناشر في الدولة تذوب في واحدة جزيء مستوى

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single ...

Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6]3+ with L-arginine to pH 4.6. Since the hydrolysis of aqueous aluminum salts is known to produce a wide array of products with a wide range of size distributions, a variety of state-of-the-art instruments (i.e., 27Al/1H NMR, FTIR, ICP-OES, TEM-EDX, XPS, XRD, and BET) were used to characterize the synthesis products and identification of byproducts. The product, which was comprised of nanoparticles (10-30 nm), was isolated using gel permeation chromatography (GPC) column technique. Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) identified the purified material as the gibbsite polymorph of aluminum hydroxide. The addition of inorganic salts (e.g., NaCl) induced electrostatic destabilization of the suspension, thereby agglomerating the nanoparticles to yield Al(OH)3 precipitate with large particle sizes. By utilizing the novel synthetic method described here, Al(OH)3 was partially loaded inside the highly ordered mesoporous framework of MCM-41, with average pore dimensions of 2.7 nm, producing an aluminosilicate material with both octahedral and tetrahedral Al (Oh/Td = 1.4). The total Al content, measured using energy-dispersive X-ray spectrometry (EDX), was 11% w/w with a Si/Al molar ratio of 2.9. A comparison of bulk EDX with surface X-ray photoelectron spectroscopy (XPS) elemental analysis provided insight into the distribution of Al within the aluminosilicate material. Furthermore, a higher ratio of Si/Al was observed on the external surface (3.6) as compared to the bulk (2.9). Approximations of O/Al ratios suggest a higher concentration of Al(O)3 and Al(O)4 groups near the core and external surface, respectively. The newly developed synthesis of Al-MCM-41 yields a relatively high Al content while maintaining the integrity of the ordered silica framework and can be used for applications where hydrated or anhydrous Al2O3 nanoparticles are advantageous.

An ultrafine aluminum hydroxide nanoparticle suspension was prepared via the controlled titration of [Al(H2O)]3+ with L-arginine to pH 4.6 with and without cage-effect confinement within mesoporous channels of MCM-41.

إعداد سهل من الجسيمات هيدروكسيد الألومنيوم متناهية الصغر مع أو بدون ميسوبورووس مسم-41 في البيئات المحيطة

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6]3+ with L-arginine to pH 4.6. Since the hydrolysis ...

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energy-dispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

جانبا إلى جانب ربط النانو تشالكوجينيدي شكل متباين الكادميوم غرواني

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to investigate the lipid raft hypothesis. Numerous studies, however, neglect the impact of physiological solution conditions. On that account, the current work presents the effect of high-salinity buffer and trans-membrane solution asymmetry on liquid-liquid phase separation in charged GUVs grown from dioleylphosphatidylglycerol, egg sphingomyelin, and cholesterol. The effects were studied under isothermal and varying temperature conditions.
We describe equipment and experimental strategies applicable for monitoring the stability of coexisting liquid domains in charged vesicles under symmetric and asymmetric high-salinity solution conditions. This includes an approach to prepare charged multicomponent GUVs in high-salinity buffer at high temperatures. The protocol entails the option to perform a partial exchange of the external solution by a simple dilution step while minimizing the vesicle dilution. An alternative approach is presented utilizing a microfluidic device that allows for a complete external solution exchange. The solution effects on phase separation were also studied under varying temperatures. To this end, we present the basic design and utility of an in-house built temperature control chamber. Furthermore, we reflect on the assessment of the GUV phase state, pitfalls associated with it and how to circumvent them.

Experiments on phase separated giant unilamellar vesicles (GUVs) frequently neglect physiological solution conditions. This work presents approaches to study the effect of high-salinity buffer on liquid-liquid phase separation in charged multicomponent GUVs as a function of trans-membrane solution asymmetry and temperature.

مرحلة السلوك من حويصلات مشحونة بظروف الحل المتماثلة وغير المتماثلة رصدها بالفحص المجهري الأسفار

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to ...

Synthesis of Core-shell Lanthanide-doped Upconversion Nanocrystals for Cellular Applications

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical properties, which allow for the absorption of near-infrared (NIR) light and can subsequently convert it into multiplexed emissions that span over a broad range of regions from the UV to the visible to the NIR. This article presents detailed experimental procedures for high-temperature co-precipitation synthesis of core-shell UCNs that incorporate different lanthanide ions into nanocrystals for efficiently converting deep-tissue penetrable NIR excitation (808 nm) into a strong blue emission at 480 nm. By controlling the surface modification with biocompatible polymer (polyacrylic acid, PAA), the as-prepared UCNs acquires great solubility in buffer solutions. The hydrophilic nanocrystals are further functionalized with specific ligands (dibenzyl cyclooctyne, DBCO) for localization on the cell membrane. Upon NIR light (808 nm) irradiation, the upconverted blue emission can effectively activate the light-gated channel protein on the cell membrane and specifically regulate the cation (e.g., Ca2+) influx in the cytoplasm. This protocol provides a feasible methodology for the synthesis of core-shell lanthanide-doped UCNs and subsequent biocompatible surface modification for further cellular applications.

A protocol is presented for the synthesis of core-shell lanthanide-doped upconversion nanocrystals (UCNs) and their cellular applications for channel protein regulation upon near-infrared (NIR) light illumination.

توليف لشل الأساسية لانثانيدات يخدر نانوكريستالس Upconversion لتطبيقات الهاتف الخلوي

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical ...

Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. Traditionally, they were synthesized through thermal cycloaddition reactions, whereas today, photocatalysis is preferred due to the mild and efficient conditions. With this focus, a new photocatalytic method for the synthesis of nitrogen-containing heterocycles is highly desired. Here, we report a protocol for the biosynthesis of cercosporin, which could function as a metal-free photocatalyst. We then illustrate cercosporin-photocatalyzed protocols for the synthesis of nitrogen-containing heterocycles 1,2,3-thiadiazoles through annulation of azoalkenes with KSCN, and synthesis of 1,4,5,6-tetrahydropyridazines [4+2] through cyclodimerization of azoalkenes under mild conditions, respectively. As a result, there is a new bridge between the microbial fermentation method and organic synthesis in a mild, cost-effective, environmentally friendly and sustainable manner.

New routes for the synthesis of nitrogen-containing heterocycles utilizing cercosporin as a metal-free photocatalyst were developed.

سيركوسبورين-Photocatalyzed [4+1]- و [4+2]-الإبطال من Azoalkenes تحت ظروف خفيفة

The interest on nitrogen-containing heterocycles has expanded rapidly in the synthetic community since they are important motifs for new drugs. ...

A Femtoliter Droplet Array for Massively Parallel Protein Synthesis from Single DNA Molecules

Advances in spatial resolution and detection sensitivity of scientific instrumentation make it possible to apply small reactors for biological and chemical research. To meet the demand for high-performance microreactors, we developed a femtoliter droplet array (FemDA) device and exemplified its application in massively parallel cell-free protein synthesis (CFPS) reactions. Over one million uniform droplets were readily generated within a finger-sized area using a two-step oil-sealing protocol. Every droplet was anchored in a femtoliter microchamber composed of a hydrophilic bottom and a hydrophobic sidewall. The hybrid hydrophilic-in-hydrophobic structure and the dedicated sealing oils and surfactants are crucial for stably retaining the femtoliter aqueous solution in the femtoliter space without evaporation loss. The femtoliter configuration and the simple structure of the FemDA device allowed minimal reagent consumption. The uniform dimension of the droplet reactors made large-scale quantitative and time-course measurements convincing and reliable. The FemDA technology correlated the protein yield of the CFPS reaction with the number of DNA molecules in each droplet. We streamlined the procedures about the microfabrication of the device, the formation of the femtoliter droplets, and the acquisition and analysis of the microscopic image data. The detailed protocol with the optimized low running cost makes the FemDA technology accessible to everyone who has standard cleanroom facilities and a conventional fluorescence microscope in their own place.

The overall goal of the protocol is to prepare over one million ordered, uniform, stable, and biocompatible femtoliter droplets on a 1 cm2 planar substrate that can be used for cell-free protein synthesis.

A مجموعة القطيفة Femtoliter تخليق البروتين موازية على نطاق واسع من جزيئات الحمض النووي واحد

Advances in spatial resolution and detection sensitivity of scientific instrumentation make it possible to apply small reactors for biological and ...

Synthesis of Aptamer-PEI-g-PEG Modified Gold Nanoparticles Loaded with Doxorubicin for Targeted Drug Delivery

Due to drug resistance and toxicity in healthy cells, use of doxorubicin (DOX) has been limited in clinical cancer therapy. This protocol describes the designing of poly(ethylenimine) grafted with polyethylene glycol (PEI-g-PEG) copolymer functionalized gold nanoparticles (AuNPs) with loaded aptamer (AS1411) and DOX through amide reactions. AS1411 is specifically bonded with targeted nucleolin receptors on cancer cells so that DOX targets cancer cells instead of healthy cells. First, PEG is carboxylated, then grafted to branched PEI to obtain a PEI-g-PEG copolymer, which is confirmed by 1H NMR analysis. Next, PEI-g-PEG copolymer coated gold nanoparticles (PEI-g-PEG@AuNPs) are synthesized, and DOX and AS1411 are covalently bonded to AuNPs gradually via amide reactions. The diameter of the prepared AS1411-g-DOX-g-PEI-g-PEG@AuNPs is ~39.9 nm, with a zeta potential of -29.3 mV, indicating that the nanoparticles are stable in water and cell medium. Cell cytotoxicity assays show that the newly designed DOX loaded AuNPs are able to kill cancer cells (A549). This synthesis demonstrates the delicate arrangement of PEI-g-PEG copolymers, aptamers, and DOX on AuNPs that are achieved by sequential amide reactions. Such aptamer-PEI-g-PEG functionalized AuNPs provide a promising platform for targeted drug delivery in cancer therapy.

In this protocol, doxorubicin-loaded AS1411-g-PEI-g-PEG modified gold nanoparticles are synthesized via three-step amide reactions. Then, doxorubicin is loaded and delivered to target cancer cells for cancer therapy.

توليف Aptamer-PEI-g-PEG الجسيمات النانوية الذهبية المعدلة المحملة بدوكسوروبيسين لتسليم الأدوية المستهدفة

Due to drug resistance and toxicity in healthy cells, use of doxorubicin (DOX) has been limited in clinical cancer therapy. This protocol describes the ...